Source.actorRef

Materialize an ActorRef of the classic actors API; sending messages to it will emit them on the stream.

Actor interop operators

Signature

Source.actorRefSource.actorRef

Description

Materialize an ActorRef, sending messages to it will emit them on the stream. The actor contains a buffer but since communication is one way, there is no back pressure. Handling overflow is done by either dropping elements or failing the stream; the strategy is chosen by the user.

The stream can be completed successfully by sending the actor reference a akka.actor.Status.Success. If the content is akka.stream.CompletionStrategy.immediately the completion will be signaled immediately. Otherwise, if the content is akka.stream.CompletionStrategy.draining (or anything else) already buffered elements will be sent out before signaling completion. Sending akka.actor.PoisonPill will signal completion immediately but this behavior is deprecated and scheduled to be removed. Using akka.actor.ActorSystem.stop to stop the actor and complete the stream is not supported.

See also:

Examples

Scala
import akka.Done
import akka.actor.ActorRef
import akka.stream.OverflowStrategy
import akka.stream.CompletionStrategy
import akka.stream.scaladsl._

val source: Source[Any, ActorRef] = Source.actorRef(
  completionMatcher = {
    case Done =>
      // complete stream immediately if we send it Done
      CompletionStrategy.immediately
  },
  // never fail the stream because of a message
  failureMatcher = PartialFunction.empty,
  bufferSize = 100,
  overflowStrategy = OverflowStrategy.dropHead)
val actorRef: ActorRef = source.to(Sink.foreach(println)).run()

actorRef ! "hello"
actorRef ! "hello"

// The stream completes successfully with the following message
actorRef ! Done
Java
import akka.actor.ActorRef;
import akka.actor.Status.Success;
import akka.stream.OverflowStrategy;
import akka.stream.CompletionStrategy;
import akka.stream.javadsl.Sink;
import akka.testkit.TestProbe;

int bufferSize = 100;
Source<Object, ActorRef> source =
    Source.actorRef(
        elem -> {
          // complete stream immediately if we send it Done
          if (elem == Done.done()) return Optional.of(CompletionStrategy.immediately());
          else return Optional.empty();
        },
        // never fail the stream because of a message
        elem -> Optional.empty(),
        bufferSize,
        OverflowStrategy.dropHead());

ActorRef actorRef = source.to(Sink.foreach(System.out::println)).run(system);
actorRef.tell("hello", ActorRef.noSender());
actorRef.tell("hello", ActorRef.noSender());

// The stream completes successfully with the following message
actorRef.tell(new Success(CompletionStrategy.draining()), ActorRef.noSender());

Reactive Streams semantics

emits when there is demand and there are messages in the buffer or a message is sent to the ActorRef

completes when the actor is stopped by sending it a particular message as described above

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